In manufacture of various microelectronic devices electrically insulating materials are applied to isolate and protect various electrically conducting and semiconducting components. Frequently, it is desirable to form a pattern or image from the electrically insulating materials, thereby defining conductive pathways in the electrically insulating materials.
Depending upon the application, various materials have been used as the electrically insulating materials. The pattern or image may be formed in a variety of manners depending upon the type of insulating material selected.
Thermosetting polymers and oligomers made from benzocyclobutene containing monomers (also referred to as cyclobutarenes) are known to be useful as electrically insulating materials in electronic devices. Commercial examples of such materials based on the 1,3-bis(2-bicyclo[4.2.0]octa 1,3,5-trien-3-yl ethenyl)-1,1,3,3 tetramethylsiloxane (referred to herein as DVS-bisBCB) monomer are available from The Dow Chemical Company under the tradename CYCLOTENE™. Typically, these materials are applied to a substrate by standard coating techniques (e.g. spin coating). They are cured or cross-linked by heating, and they are patterned by etching. Recognition of the desirability of having resins which do not require additional coating steps used in standard lithographic etching has led to the development of CYCLOTENE 4000 resins, which are negative tone photosensitive compositions, in which the portion of the material which is not exposed to the activating radiation is removed by solvent during development. After patterning, the remaining resin is cured.
U.S. Pat. No. 6,361,926 taught that benzocyclobutene based oligomers and polymers could be made soluble in such alkaline aqueous solutions by the inclusion of acid functionality in the oligomer. This patent taught that photosensitive compositions could be made by mixing the benzocyclobutene oligomer formulation with a photoinitiator (to provide negative tone systems) or dissolution inhibitor/photoactive agent (to provide positive tone systems).